征象/症状
无法根据症状和征象，对 COVID-19 与社区获得性呼吸道感染加以鉴别。然而，发热在流感中并非那么常见。流涕、咽痛、肌痛、头痛和呼吸困难则更为常见。[713]Pormohammad A, Ghorbani S, Khatami A, et al. Comparison of influenza type A and B with COVID-19: a global systematic review and meta-analysis on clinical, laboratory and radiographic findings. Rev Med Virol. 2020 Oct 9:e2179.
https://onlinelibrary.wiley.com/doi/10.1002/rmv.2179
http://www.ncbi.nlm.nih.gov/pubmed/33035373?tool=bestpractice.com
[714]Czubak J, Stolarczyk K, Orzeł A, et al. Comparison of the clinical differences between COVID-19, SARS, influenza, and the common cold: a systematic literature review. Adv Clin Exp Med. 2021 Jan;30(1):109-14.
https://www.advances.umed.wroc.pl/pdf/2021/30/1/109.pdf
http://www.ncbi.nlm.nih.gov/pubmed/33529514?tool=bestpractice.com
一项病例对照研究中，新发嗅觉和/或味觉障碍较为不常见。[715]Beltrán-Corbellini Á, Chico-García JL, Martínez-Poles J, et al. Acute-onset smell and taste disorders in the context of COVID-19: a pilot multicenter PCR-based case-control study. Eur J Neurol. 2020 Sep;27(9):1738-41.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7264557
http://www.ncbi.nlm.nih.gov/pubmed/32320508?tool=bestpractice.com
更常见于儿童。[716]Solomon DA, Sherman AC, Kanjilal S. Influenza in the COVID-19 era. JAMA. 2020 Oct 6;324(13):1342-3.
https://jamanetwork.com/journals/jama/fullarticle/2769676
http://www.ncbi.nlm.nih.gov/pubmed/32797145?tool=bestpractice.com
患上 COVID-19 的儿童通常年龄较大，且比起流感儿童患者更可能患有合并症、出现发热、胃肠道症状、头痛和胸痛。[717]Song X, Delaney M, Shah RK, et al. Comparison of clinical features of COVID-19 vs seasonal influenza A and B in US children. JAMA Netw Open. 2020 Sep 1;3(9):e2020495.
https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2770250
http://www.ncbi.nlm.nih.gov/pubmed/32897374?tool=bestpractice.com
可能出现混合感染，但与死亡不具显著相关性。[718]Guan Z, Chen C, Li Y, et al. Impact of coinfection with SARS-CoV-2 and influenza on disease severity: a systematic review and meta-analysis. Front Public Health. 2021 Dec 10;9:773130.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8703010
http://www.ncbi.nlm.nih.gov/pubmed/34957025?tool=bestpractice.com
儿童患者和危重患者混合感染率较高。[719]Dao TL, Hoang VT, Colson P, et al. Co-infection of SARS-CoV-2 and influenza viruses: a systematic review and meta-analysis. J Clin Virol Plus. 2021 Sep;1(3):100036.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8349735
http://www.ncbi.nlm.nih.gov/pubmed/35262019?tool=bestpractice.com
辅助检查
只有进行检测，方能区分流感感染和 COVID-19，明确是否存在混合感染。
RT-PCR：甲型或乙型流感病毒 RNA 检测呈阳性；SARS-CoV-2 病毒 RNA 检测呈阴性（有可能发生混合感染）。
胸部 X 线检查：呈现异常的可能性较小。[713]Pormohammad A, Ghorbani S, Khatami A, et al. Comparison of influenza type A and B with COVID-19: a global systematic review and meta-analysis on clinical, laboratory and radiographic findings. Rev Med Virol. 2020 Oct 9:e2179.
https://onlinelibrary.wiley.com/doi/10.1002/rmv.2179
http://www.ncbi.nlm.nih.gov/pubmed/33035373?tool=bestpractice.com
胸部 CT：新兴证据表明 CT 可用于鉴别流感和 COVID-19。COVID-19 患者更易出现环状或线性浑浊、铺路石征、血管扩张，以及小叶间隔增厚，但结节、树芽征、支气管扩张症和胸腔积液则较少出现。[720]Liu M, Zeng W, Wen Y, et al. COVID-19 pneumonia: CT findings of 122 patients and differentiation from influenza pneumonia. Eur Radiol. 2020 Oct;30(10):5463-9.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7216854
http://www.ncbi.nlm.nih.gov/pubmed/32399710?tool=bestpractice.com
[721]Yin Z, Kang Z, Yang D, et al. A comparison of clinical and chest CT findings in patients with influenza A (H1N1) virus infection and coronavirus disease (COVID-19). AJR Am J Roentgenol. 2020 May 26:1-7.
https://www.ajronline.org/doi/10.2214/AJR.20.23214
http://www.ncbi.nlm.nih.gov/pubmed/32452731?tool=bestpractice.com
炎性标志物和凝血筛查：越来越多证据表明，与 COVID-19 相比，流感患者炎性标志物（乳酸脱氢酶、红细胞沉降率、C 反应蛋白）和凝血指标未达同样高度。[722]Luo Y, Yuan X, Xue Y, et al. Using the diagnostic model based on routine laboratory tests to distinguish patients infected with SARS-CoV-2 from those infected with influenza virus. Int J Infect Dis. 2020 May 1;95:436-40.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7194039
http://www.ncbi.nlm.nih.gov/pubmed/32371192?tool=bestpractice.com
